Powell was acting on good faith. His post-festum testimonials indicate that he was suspicious of the intel and had expressed his discomfort - to which he had been repeatedly re-assured by the people in charge of intel that intel was good.
Thus your claim that "Bush government was looking for any excuse" is wrong - as Powell himself has been a major part of Bush government.
Implying that Powell has been a victim of conspiracy is quite a bit of a conspiracy theory in itself. He might have been lied to due to corruption - or "just" due to incompetence.
What I am trying to argue here is - that somebody, somewhere should start an inquiry on how it was possible that Powell has been fed bad information. If there was a conspiracy - the perpetrators should be indicted for treason. If the reason is incompetence (which is a worse option IMO) - then a major overhaul of the intelligence agencies would be in order.
I do understand that the pragmatic option for numerous reasons has been to just "forget" about it - that may not be the best long term solution.